Recently various documents and contents are generated and distributed as a digital content readable by computer, according to the rapid development of computer, internet, and storage devices. Unfortunately, the digital content have fatal problem that is too easy to copy and distribute illegally the original one with same quality. Though there are a lot of time, effort, and capital invested into making the valuable digital content, it is difficult to expect for the development of the digital content industry without any proper and legal effort to protect the copyrights.
The Digital Rights Management(DRM) technology moves into the limelight as the core technology enabling to block thoroughly illegal copy and unauthorized distribution of digital content and realize the profit from digital content service business. Therefore the whole global countries and companies are very interested in the copyright protection of digital content just like the examples of Napster.com in the U.S., Soribada.com in the South Korea and Warez sites for the exchange of MP3 files or illegal movie files, which is stirred with the copyright conflict. DRM system is pivotal technology to build up the copyright protection and proper distribution system of digital content, which utilized by the methods such as online and offline digital networks.
If the DRM system is applied to the content service, the possibility of copyright infringement is abruptly decreased because of the content encryption. The customer who wants to view the digital content, therefore, must pay the proper content fee, which is very important for the enlargement of digital content industry. In addition, DRM is not only the copyright protection technology but also the potential technology for the new selling and distribution of digital content, for an example of super-distribution.
DRM system may be divided mainly into three categories of internet DRM for PC(Personal computer), mobile DRM for cellular phone and PDA(Personal Digital Assistants), and set-top box DRM for Home VOD(Video On Demand) service, according to the application field. Also DRM system may be divided into DRM for document content security and for multimedia content security, according to the application object. In detail, DRM system for multimedia content security may be distinguished as download support or VOD/live streaming support according to the technological difficulty.
The international companies for DRM solution are Intertrust which first started internationally DRM technology development in 1990, Microsoft, IBM, Contentguard, Realnetworks, Lockstream, Digimarc, Divxnetworks, Entriq, Sealedmedia, Sony, Nec, etc. In Korea, there are about over 30 venture companies developing ardently the technology and competing for commercialization of the DRM system.
Although there are many positive expectations in the market, the commercialization of DRM system is very slowly proceeding. It is mainly due to the technological weakness, according to the analysis of the released DRM solutions up to now.
For examples, most of DRM solutions compel an end user to endure the installation of a specific viewer program for DRM, and there are limitations of the content formats supported and low standardization. First of all, the specific viewer program for DRM gives end user a reluctance of DRM applied and has a restriction of file format supported. Since the specific viewer program is continuously needed to be developed and upgraded, it is main fault for DRM Company and end user.
In addition, most of DRM system can support the content service not by streaming but download up to now. Though only a few DRM companies such as Microsoft and Realnetworks have developed the DRM for streaming, no DRM solution for live streaming is released until now.
Microsoft has expanded its own market supremacy to distribute DRM SDK(Software Development Kit) what is called WMRM(Windows Media Rights Manager) for free because the company assumed that the DRM market is not fully expanded. Even though the effort of the Microsoft, the Microsoft's DRM solution has the weak point that its DRM technology is only applicable to its own file formats.
The streaming technology, which is the process of playing a digital file while it is still downloading and lets a user view and hear digitalized content such as video, sound and animation, is now popular for the content service. Unlike download, streaming technology is not needed to receive the all contents data from external network server and it plays repeatedly a part of content data downloaded. Streaming is very useful data transmission technology for the prevention of copyright infringement, content service of very large file size, and removal of inconvenient waiting for download. By using streaming technology, the content data transferred from external network is not saved at HDD of client system but temporarily saved and played on RAM(Random Access Memory) for content service. Streaming may be divided into VOD streaming and live streaming. The content of VOD streaming must be in advance manufactured and be deployed on the content server and may be transferred to client system dependent on the user's request. In live streaming, the content of online performance, news, and sports game must be transferred in real-time to client system. In the case of HTTP streaming, a part of digital content is played continuously and saved simultaneously at HDD during downloading.
But it is proved that streaming is no more secure content service, after Hoonnet Inc. in Korea releases the “Hinet Recorder” for the recording of the streaming data. Hinet Recorder can record the streaming content with same quality of original content and illegal copy products are very spread through Warez sites. It is proven that streaming technology is very weak to illegal copy.
In this invention, client system is meant as general information processing system such as PC, Notebook, PDA, cellular phone, set-top box, digital TV, Telematics device, etc. The general information processing system is composed of a CPU, volatile storage device such as memory, non-volatile storage device such as hard disk drive, and input/output device such as keyboard or monitor, etc. and is connected with wire or wireless communication devices for internal and external communication, respectively. In addition, the information processing system is composed of hardware and software, the device driver is an interface software to activate the specific devices, which play a role of connecting with device.
There are various device drivers in the information processing system which may be located like layer stacks. One of the representative device drivers is a file system device driver that is responsible for the control and management of storage device such as HDD and files and directories. The network filter driver is a famous driver for the control and management of network device for external communication. There are a lot of device drivers for the control of each device, such as virtual memory, CPU, process management, multitasking, printer, keyboard, monitor, etc. The filter driver can be programmed for the specific function and located properly like filter in the layer stack of device drivers.
Recently Teruten Inc. proposes the patent of “The security system for the secure transmission and execution of digital data”(Korea Patent Pending No. 10-2001-34583) for DRM system without a specific viewer program. The main component of above patent pending is composed of specific storage region, file system filter driver, and file filter controller. Since the file system filter driver play role in the filtering operation, only approved application program can approach the specific storage region at HDD. The above patent pending has a few weaknesses. The file system filter driver is well known to control the application program and encrypt/decrypt a file data. Because the DRM system in above technique needs to an additional establishment of storage region, in which a decrypted file is stored, for the special management, there may be some dangerous for data security. Additionally, there is an inconvenience by registration and management of all approved programs into file filter driver and detailed explanation for technology development is missing in above invention. The focus of above invention is mainly constricted to the DRM system proposal for higher interoperability between various DRM solutions manufactured by different companies.
Also Teruten Inc. proposed another patent pending of “A system and method for protection of digital data executed by stream method”(Korea Patent Pending No. 10-2001-50151). Although the title of patent is expressed as “stream method”, it could not be applied to content service by general streaming technology because of filter system filter driver. Since the content must be saved in the HDD and transferred to file filter driver, the DRM system proposed in this invention could not support the content service by VOD or live streaming.
On the other hand, there is a powerful invention of data security related with file filter driver proposed by Infraworks Inc. The title of patent is “System and method for providing data security” (PCT Pending No. WO 0125870/Korea Patent Pending No. 10-2001-7006901). But the core technology is related file filter driver of controlling the storage device such as HDD, which is composed of packager and receiver based on function of file filter driver. Since this technology is constricted to file security by download method, it could not be applied to the streaming service by temporarily save and usage on RAM.
Different with prior art, Coretrust Inc. proposed a unique invention of DRM technology whose title is “A method and system for information protection for digital contents” (Korea Patent Pending No. 10-2002-1916). In this invention, it is supposed to control the general application program without a specific viewer program using the control of file system filter driver. According to this technology, a useful and creative DRM system can be manufactured for content service of download and HTTP streaming.
Coretrust also proposed another patent whose title is “A system and method of the information protection for multimedia streaming content, and recorded medium thereof” (Korea Patent Pending No. 10-2002-73773). In this invention, a new DRM system without specific viewer program for VOD and live streaming is supposed by using of network filter driver. Network filter driver in this invention play an important role of filtering operation of encrypted content data received by streaming method.